Use of a flexible instrument (a "scope") to examine the ileum which is the lowest part of the small intestine. Ileoscopy is usually accomplished during colonoscopy, when the instrument tip passes first through the rectum and the lower colon and eventually reaches the area where the ileum and the colon (the large bowel) connect. The examiner can look at the ileum and take biopsy samples of the lining tissues, if needed.